[InstCombine] remove dead code for add (select cond, (sub), 0); NFC

This pattern is handled more generally in SimplifySelectsFeedingBinaryOp().
Tests to confirm that added to the add.ll test file in the previous commit.

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
index c8b3fd0..b80064b 100644 (file)
--- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -1378,31 +1378,6 @@ Instruction *InstCombinerImpl::visitAdd(BinaryOperator &I) {
   if (haveNoCommonBitsSet(LHS, RHS, DL, &AC, &I, &DT))
     return BinaryOperator::CreateOr(LHS, RHS);
 
-  // add (select X 0 (sub n A)) A  -->  select X A n
-  {
-    SelectInst *SI = dyn_cast<SelectInst>(LHS);
-    Value *A = RHS;
-    if (!SI) {
-      SI = dyn_cast<SelectInst>(RHS);
-      A = LHS;
-    }
-    if (SI && SI->hasOneUse()) {
-      Value *TV = SI->getTrueValue();
-      Value *FV = SI->getFalseValue();
-      Value *N;
-
-      // Can we fold the add into the argument of the select?
-      // We check both true and false select arguments for a matching subtract.
-      if (match(FV, m_Zero()) && match(TV, m_Sub(m_Value(N), m_Specific(A))))
-        // Fold the add into the true select value.
-        return SelectInst::Create(SI->getCondition(), N, A);
-
-      if (match(TV, m_Zero()) && match(FV, m_Sub(m_Value(N), m_Specific(A))))
-        // Fold the add into the false select value.
-        return SelectInst::Create(SI->getCondition(), A, N);
-    }
-  }
-
   if (Instruction *Ext = narrowMathIfNoOverflow(I))
     return Ext;